1. Field of the Invention
The present invention relates to an apparatus for removing a surface layer of animal muscular tissue, particularly a fish fillet surface layer including the fish skin, the apparatus comprising a skinning roller driven in rotary manner and having a gripping circumferential surface, a paring or skinning knife whose cutting edge faces said circumferential surface, and a presser surface positioned equidistantly of the circumferential surface.
2. Prior Art
The prior art discloses several apparatus for this purpose.
E.g. German Patent No. 21 36 038 discloses a machine for removing the rind from hams or the like. This machine is provided, above its derinding knife, carried by a presser shoe, with a second blade for the simultaneous cutting off of a fat side from the rind-removed ham. This second blade can be set to different longitudinal inclinations with respect to the rind-removing knife and its mounting, together with the presser shoe, is pivotably arranged in such a way that the presser surface of the presser shoe is displaceable under a radial component and the cutting edge of the second blade is displaceable under a tangential component with respect to the skinning roller. When using this apparatus, the rind is removed from the ham to be processed and simultaneously a separate fat slice is obtained.
When skinning fish fillets, particularly of those fish having a dark-coloured layer of pasty consistency between the skin and the muscular flesh, such as e.g. pollock (pollachius) and hake (marluccius), it is desirable to produce fillets which are free from this layer.
Corresponding machines are in use. It is a fundamental feature thereof that they have, in accordance e.g. with German Patent No. 17 53 121, a driven refrigerating freezing drum disclosed for the first time in U.S. Pat. No. 1,921,440. For the purpose of a reliable transport of the fish fillets to be processed their skin sides are frozen onto this drum against the resistance caused by the skinning knife.
As a result of the high constructional and energy costs linked with this concept, many efforts have been made over the years to find a less complicated and costly system which, at the same time, is suitable to be integrated into a filleting line of the presently standard performance level.
Due to its simplicity, attention has been concentrated on the presser shoe - stationary knife principle. However, up to now the efforts have not met with the necessary success, because any manipulation on the presser shoe or knife either has a negative influence on the critical cutting phase and/or in general the reliability of the passage of the fillet. It is for this reason that the principle of the first-mentioned prior art has failed in the processing of fish fillets and in addition the separately produced material layer having no internal cohesion leads to premature clogging of the machine.
3. Object of the Invention
It is therefore a primary and essential object of the present invention to find and suggest a concept which is free from the above deficiencies.